Mitochondria are intracelluar organels that convert the energy from food into a form that cells can use. Although most of the DNA is packed into chromosomes within the nucleus, mitochondria also have a small amount of their own DNA. This genetic material is known as mitochondrial DNA (mtDNA). Mitochondrial DNA in humans spans about 16,500 DNA bps, representing a small fraction of the total celluar DNA.
Mitochondrial DNA contains 37 genes, which are essential for normal mitochondrial function. Thirteen of these genes encode enzymes involved in oxidative phosphorylation. Oxidative phosphorylation is a process that uses oxygen and simple sugars to create adenosine triphosphate (ATP), the main source of energy in the cell. The remaining genes encode for transfer RNA (tRNA) and ribosomal RNA (rRNA).
Many genetic conditions are related to changes in particular mitochondrial genes.